What is $1 in Swift?

I'm curious, could you explain to me what exactly $1 in Swift represents? I've heard about Swift being used in the world of finance and cryptocurrency, but I'm not entirely clear on how the value of $1 translates within this context. Is it a specific amount of a certain cryptocurrency? Or does it have a different meaning altogether? I'd appreciate it if you could provide a clear and concise explanation to help me better understand this concept.